CLIPPERS, chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids: A challenge in neurological practice, clinical landmarks (Review)

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a relatively newly discovered and characterized condition affecting the central nervous system (CNS) that involves the brainstem almost ubiquitously and that focuses primarily on the pons. Characteristically, CLIPPERS represents a combination of clinical symptoms related to the pathology of the brainstem in particular and has a characteristic appearance on magnetic resonance imaging (MRI), with punctate and curvilinear gadolinium enhancement 'peppering' the pons. The lesions can be viewed via neuroimaging with a predominance in the pons and adjacent rhombencephalic structures, such as the cerebellar peduncles, cerebellum, medulla, and middle brain. These lesions may also spread and appear in other areas of the brain such as the thalamus or white matter. As the name suggests, this clinical syndrome responds to immunosuppressive treatment based on glucocorticosteroids (GCSs), expressed as both clinical and radiological improvements. Support for this treatment is required for a long period, since exacerbations may occur without. Thus, the diagnosis of CLIPPERS has garnered increased attention from clinicians and the active exclusion of differential alternative diagnoses is needed. A specific biomarker of serum or cerebrospinal fluid (CSF) for this condition has not been discovered. The pathophysiology of this condition is not fully elucidated, and it is not yet clear whether CLIPPERS is a disease in its own right or is the culmination of several already known syndromes. Clinicians and radiologists should pay close attention to this condition as it is relatively easy to treat and patients can benefit from the early introduction of GCSs, which can produce significant results through long-term immunosuppression. Taking into account previous reports in the literature, which currently include over 50 cases reported as CLIPPERS, this analysis addressed the clinical features, and paraclinical and differential diagnoses of cases described in the literature.